🌍 Terraform Overview

Terraform by HashiCorp is an Infrastructure as Code (IaC) tool that enables you to provision, manage, and version cloud infrastructure using a declarative language (HCL – HashiCorp Configuration Language).

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🧱 Core Terraform Components Explained

1️⃣ variable – Input Configuration

Variables are used to pass dynamic values into your configuration. This makes your code reusable and configurable for different environments (dev, test, prod, etc.).

variable "region" {
  description = "The AWS region to deploy resources in"
  type        = string
  default     = "us-east-1"
}

You access it using:

provider "aws" {
  region = var.region
}

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2️⃣ sets – Unique Unordered List

A set is a collection of unique values with no particular order. It prevents duplication and is useful when order doesn't matter (like availability zones).

variable "azs" {
  type = set(string)
  default = ["us-east-1a", "us-east-1b"]
}

Terraform ensures values are unique.

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3️⃣ map – Key-Value Pairs

A map allows you to define dynamic lookups using keys. It's useful for selecting values based on a condition like a region or environment.

variable "instance_amis" {
  type = map(string)
  default = {
    us-east-1 = "ami-0c55b159cbfafe1f0"
    us-west-2 = "ami-0a91cd140a1fc148a"
  }
}

Usage:

ami = var.instance_amis[var.region]

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4️⃣ object – Structured Complex Data

An object is used to group multiple named attributes together into a single variable. It’s ideal for configs like database settings or tagging conventions.

variable "db_config" {
  type = object({
    engine         = string
    engine_version = string
    instance_class = string
  })

  default = {
    engine         = "mysql"
    engine_version = "8.0"
    instance_class = "db.t3.micro"
  }
}

Usage:

resource "aws_db_instance" "example" {
  engine         = var.db_config.engine
  engine_version = var.db_config.engine_version
  instance_class = var.db_config.instance_class
}

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5️⃣ module – Reusable Terraform Code

Modules are containers for reusable Terraform configurations. They let you organize code logically (e.g., separate modules for VPC, EC2, RDS).

module "vpc" {
  source = "./modules/vpc"
  cidr_block = "10.0.0.0/16"
  azs        = var.azs
}

You can create a module once and call it with different inputs as needed.

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🚀 Why Use These Components?

variable: Makes code dynamic and flexible.

set: Ensures uniqueness in lists (e.g., AZs, ports).

map: Easily manage environment- or region-specific values.

object: Organize related settings into structured data.

module: Encapsulate logic, reduce repetition, and improve code reusability.